Jacob deGrom ranks fourth in the majors in ERA and Noah Sydnergaard fifth, and the Mets as a team have the third-best starter ERA.

Yet it feels like the rotation has just not been the force expected. Is that perception? Reality? A combo of both?

In the best-case scenario, the Mets were going to be a daily dose of dominance with deGrom, Syndergaard, Matt Harvey and Steven Matz thriving, and Zack Wheeler adding to the bounty for the second half.

Because of the velocity with which each throws, the worst scenario always lingered, too, with a couple of Tommy John surgeries scheduled.

Neither extreme occurred. But doesn’t it feel like what has happened is one of the worst projections that could have been imagined in March?

Harvey never pitched well and eventually needed surgery for thoracic outlet syndrome and was lost for the season. Wheeler suffered setbacks that probably make him a September option only.

Syndergaard and Matz both came down with bone spurs in their elbows. Syndergaard no longer looks like the force of nature of the first two months. He has not fallen apart, but there is an awful lot of labor now to be very good. The magical slider is something less, his impenetrable glean shattered. Since the beginning of June, Matz has a 4.81 ERA and .825 OPS against in 11 starts.

This all becomes more pertinent now. The Mets’ overt offensive issues only became more so with Yoenis Cespedes going to the DL.

“[The rotation] is probably not as good as it was expected to be,” GM Sandy Alderson said. “It is third in the majors in ERA, but I suspect people thought it would be even better. But I do think that we have not scored runs has been part of this, as well. At some point, that begins to play with your pitching staff’s psyche.”

Alderson said he does not believe the rotation is trending the wrong way. The group’s 3.46 ERA going into Thursday is equivalent to the 3.44 of last year — and that is with run scoring up from 2015.

Alderson feels a lot of the negative perceptions are based on Harvey’s performance and then absence, recognizing he has the biggest persona of the group. But Alderson did agree the rotation results have lacked the consistent excellence he was anticipating.

Can that reverse? Well, deGrom is beginning to push into the Cy Young conversation, especially with Clayton Kershaw out injured. There seems to be belief around the Mets that Syndergaard is dealing more with a long-season malaise than that he is being weighed down by pain or exhaustion. Can Matz find a groove? Can Wheeler make a four- or five-start impact over the final month? Can Bartolo Colon, author of 6 ²/₃ innings of one-run ball Thursday night to beat the Yankees, continue to be this year what he was last season — a blessing?

The offense was supposed to be better that this, but still, the rotation was supposed to carry the Mets.

Nothing has changed.

Girardi, Collins better get used to familiar questions

Within a half-hour, first Joe Girardi and then Terry Collins were asked about their most polarizing issues at press conferences Thursday. And neither did a good job of restraining his annoyance.

Girardi has enjoyed answering Alex Rodriguez-related questions as much as a six-game losing streak. But he had to know more were coming. Rodriguez did not start Wednesday against a lefty (Steven Matz) and did not start Thursday against Bartolo Colon, against whom he was 23-for-56 with eight homers.

Terry Collins and Joe GirardiPaul J. Bereswill (2)

Girardi pointed out those are “numbers from years and years ago” and became ornery in challenging whether reporters even knew when last the two faced each other in 2012, Rodriguez was 1-for-6 off Colon and you would have to go back to 2007 to find their previous matchups. He was right about all of that. Right that where the Yanks are, they should be playing someone else besides Rodriguez to try to win now or to see them for the future.

But understand Girardi pretty much never says anything negative about a player — he will find the glory in a hitter’s four-strikeout performance — so for him to cite the stats speaks to his annoyance about the matter. It also suggests he is the one making the lineups, something he confirmed by saying “no” when asked if upper management is dictating that Rodriguez not play.

As for Collins, his agitation was more manifest than Girardi’s over whether Yoenis Cespedes’ golfing Wednesday afternoon on a bad quad had any impact on him eventually winding up on the DL. Collins would not even let a reporter finish a question, saying: “Seriously, don’t go there. This has nothing to do with it.”

It probably doesn’t. But speaking later, Sandy Alderson would only put it in the words of team doctors, saying they did not think one had anything to do with the other. Alderson also stated calmly the golfing was “bad optics” and that Cespedes’ agents have been informed by the Mets about this.

Girardi and Collins are intense guys. But they also are the main spokesmen for their organizations. They have been around long enough to know these questions are coming — they are not being asked about Richard Bleier or Erik Goeddel. This is A-Rod and Cespedes, the two lightning rods of the New York teams (while Matt Harvey is away at least). Girardi has spent most of the last 20 years with the Yankees as either player, coach, broadcaster or manager. He still lacks the skills to defuse these issues with calm, clarity and truth. Collins actually seems to be growing more peeved about such matters, which will do nothing to bring serenity to his surroundings.

Psst, guys, the questions about A-Rod and Cespedes aren’t going to stop.